Solvent for mixed cellulose esters



Patented Oct. 4, 1932 UNITED STATES PA'rE -t orrice j CHARLES S. WEBIBER AND GYRIL J. STA'UD, OF ROCHESTER, NEW YORK, ASSIGNORS TO EASTMAN KODAK company, YORK on .noonnsrnn, NEW YORK, A oonronarron or new SOLVENT non MIXED onLLuLos ns'rnns' No Drawing.

This invention relates to solvents for mixed cellulose esters.

In our copending applications Serial lflos. 341,032, filed Feb. 18, 1929, and 342,668, filed Feb. 25, 1929 there is described a serlesof mixed cellulose esters. One class of these double esters includes a radical from the alpha hydroxy acids and an acyl radlcal.

Examples of these mixed cellulose esters con 1 tain the lactic, tartaric, racemic, malic, glycollic, glycerio and mandelic acid radicals together with certain acyl rad cals. Other poly basic alpha hydroxy acids may be present. Another group of the double esters of cellulose may be classed Lmder the heading of acyl esters of cellulose contalnlng the alpha and gamma ketonic acids, the latter comprising, for example, the pyruvic (alphaketo propionic acid), alpha keto butyri c, alpha-keto-valeric and alpha-keto-caprolc acid, or the gamma keto valeric acid, laevulinic acid. An aliphatic or aromatlc acid radical may constitute the other radical in the mixed ester. These mixed cellulose esters have solubilities according to the method of their manufacture, running from acetone solubility to water solubility.

We have found that for most commercial purposes, for which these esters are adapted, the common solvents formerly known to us were not particularly suitable. A nonaqueous solvent or compound solvent, therefore, having lower boiling constituents was desirable.

It is the object of the present invention to provide a class'of solvents for the hereinabove described mixed esters of cellulose, hav-,

ing the desired characteristics.

\Ve have found that mixtures of ethylene chloride andmonohydroxy aliphatic alcohols are suitable for this purpose. The straight or branched chain aliphatic alcohols having from one to five carbon atoms are particularly well adapted as solvents of these double esters. V

The mixed esters of cellulose referred to are legion. As noted in the above patents, the solubility of each of the esters may be varied over a wide range, this change in solubility being due to'more or less of the the possiblemixed cellulose esters.

Application filed March 18, 1929. Serial No. 348,128.

hydroxy or ketonic acid radicals being substituted for the acyl radicals. Our solvent is,

therefore, not a universal solvent for all of On the other hand, our'compound solvent is suitable for all the mixed cellulose esters whichhave a solubility between approximately aqueous-alcohol and? 5% aqueous-alcohol and also the acetone soluble mixed esters.

An adequately strong and useful compound solvent may be prepared bymixing ethylene chloride with one or more of the lower mono-V hydroxy aliphatic alcohols. V By lower monohydroxy aliphatic alcohols we include those having less than five carbon atoms. While they, may be mixed in varying proportions, it is noted, by way of example, that asuitable solvent can be formed by mixing from 30 to parts'by volume of ethylene-chloride and 7 0 to 25 parts by volume of the alcohol and the amount of the mixed ester of'cellulose dissolved in the solvent can be varied to suit the 7 means of the manufacturer. But for the by dissolving one part of the mixed cellulose est-er in 4 to 8 parts by weight of the compound solvent. Other substanceswhich impart added suppleness or incombustibility or other qualities to the composition may likewise be added. V

The ingredients are of the ordinary co mercial type and sufficiently purified for the process" of film manufacture, for example, so as to give a dope which will yield films having the proper relative freedom from color. Various changes may be made, there fore, inthe proportion of the materials employed in this compound solvent for the purpose of the invention, as well as equivalents substituted therein, the examples herein presented' being merely illustrative of suitable solvents for the'mixed cellulose ester.

- Having thus described our invention, What ters Patent is: i g

1. A flowable composition of matter, com-, prising a mixed cellulose acyl ester dissolved in a mixture of ethylene chloride and a lower mon'ohydroxy aliphatic alcohol, said mixed we claim as new anddesire to secure by Let IOU ester being soluble in either acetone or 50-75% aqueous alcohol and having an acyl radical of an organic acid selected from the group consisting ofv alpha hydroxy,-alpha ketonic and gamma ketonic acids.

2. A flowable composition of matter, comprising a mixed cellulose acyl ester dissolved in a mixture of ethylene chloride and a monohydroxy aliphatic alcohol containing one to five carbon'atoms, said mixed ester being soluble in either acetone or 50-7 5% aqueous alcohol and having an acyl radical of an organic acid selected from thegroup consisting of alpha hydroxy, alpha hetonic and gamma ketonic acids. 7

. 3. A fiowable composition of matter comprising a mixed cellulose acyl ester dissolved in a solventmixture consisting of7530% of ethylene chloride and -70% of a lower g0 monohydroxy alcohol, said mixed ester be- 7 mg soluble in either acetone or 50-75% aque-f ous alcohol and having an acyl radical of an organ c acld selected from the group'consisting of the alpha hydroxy, alpha ketonic 25 and gamma'ketonic acids.

4. A flowable composition of matter com prising a mixed cellulose acyl ester dissolved in a solvent mixture consisting of-7530% of ethylene chloride and 25-70% of a monohydroxy alcohol containing one to five carbon atoms, said mixed ester being soluble in either acetone or 5075% aqueous alcohol and having an acyl radical of an organicacid selected from the group consisting of the alpha-hydroxy, alpha ketonic and gamma ketonic. acids.

5. Aflowable composition of matter comprising a cellulose acetate-acylate dissolved in a mixture of ethylene chloride and a lower monohydroxy aliphatic alcohol, the acyl radical of the ester being from an organic acid selected from the group consisting of alpha hydroxy, alpha ketonic and gamma ketonic acids; A

6. A flowable compositionof matter comprising ethylene chloride and a lower monohydroxy aliphaticalcohol in which is dis solved a mixed ester of cellulose selected from the group consisting of cellulose acerate-lactate, cellulose acetate-tartrate, cellulose acetate-racemate, cellulose acetate-malate, cellulose acetate-glycollate, cellulose acetate-glycerate and cellulose acetate-mandelate, said ester being soluble in either acetone or -75% aqueous alcohol.- 7

7. Aflowablecomposition of matter comprising a cellulose acetate-lactate dissolved in a solvent mixture comprising ethylene chloride and a lower monohydroxy aliphatic 60 alcohol.

8. A flowable composition of matter comprising a cellulose acetate-lactate dissolved in a solvent mixture comprising ethylene chloride and a lower monohydroxy aliphatic '65 alcohol, and a plasticizer. ii 

